Homogeneous low voltage electron beam irradiation (HLEBI) improved the elasticity indicated by both flexural modulus (E_f) and the maximum slope value ((dσ⁄dε)_max) of the bending stress–strain curve of carbon fiber reinforced thermoplastic polyetheretherketone (CFRTP) composite sheets with 0.50 mm thickness, although the penetration depth estimated was from 0.14 to 0.21 mm on both side surfaces. HLEBI remarkably enhanced both E_f and (dσ⁄dε)_max. The E_f at middle cumulative probability (P_E) of 0.50 for CFRTP irradiated at 0.30 MGy (kJg⁻¹) was 3.3 GPa, which was 27% higher (2.6 GPa) than for CFRTP before irradiation. Moreover, (dσ⁄dε)_max at middle cumulative probability (P_E=0.50) was more than 4.9 GPa for CFRTP irradiated at 0.30 MGy. The interfacial friction force, as well as the strengthening of both carbon fiber and polyetheretherketone probably contributed to the HLEBI effects to enhance both E_f and (dσ⁄dε)_max in the CFRTP.